The present invention relates to a method to determine the roll performance of a golf ball after being struck by a golf putter and in particular to a method to determine the launch angle of the putter face when it strikes a golf ball during the execution of a putting stroke.
In the act of fitting a putter to a given golfer it is desirable to know when the golf ball starts rolling, end over end, allowing it to travel on a true line with minimum deviation from its intended path to the hole. Conventional putter face technology typically incorporates four to six degrees of loft that causes the ball, when impacted by the striking face of a putter, to be lifted slightly as it is being propelled forward. The reason a putter is designed to lift the ball is, in part, due to the fact that the weight of the ball forms a slight depression as it lies on the grass surface during the time the golfer approaches the green and goes through a variety of pre-shot routines, such as green reading, before subsequently striking the putt. It is therefore desirable to lift the ball out of this slight depression as it is being struck to avoid friction with the ground that will negatively affect accuracy of the roll path. This lifting effect is referred to as launch angle.
Too much loft on the face of a putter, or too much launch angle, causes a ball to rotate backward in the air and, in turn, this causes the ball to skip and skid before starting to roll. The non-rolling, skipping and skidding movement of the golf ball creates additional friction with the putting surface that has a negative effect on accuracy. Not enough loft or launch angle on a putter face will drive the ball into the surface causing the ball to bounce and skip uncontrollably with a resulting adverse effect on both distance control and accuracy.
Finding the optimal launch angle is an essential part of fitting a putter to any golfer. However, not every golfer is the same in the way they hold a putter as they address the ball. For example, if a right handed golfer is right eye dominant, that individual will tend to position the hands under their right eye because this stronger eye is telling their brain that the shaft is at 90 degrees and perfectly vertical when in fact the shaft is leaning toward the right eye. By leaning the shaft back to the right, away from the target line, the golfer is adding loft to the putter face. Conversely this same right handed golfer may be left eye dominant and will slightly press their hands forward toward the target under their left eye thereby reducing loft on the putter face.
A standard way to analyze launch angle and the resulting roll of a golf ball after impact with a putter is by the use of high speed film or video. This requires the use of expensive video equipment, special lighting and a play back monitor. The ball must also be marked with a special T shaped indicia to register the rotation of the ball as it moves forward after impact. The process of setting up the ball correctly for the camera, recording the impact and movement of the ball, and rewinding and playing back the ball's performance is time consuming and lacks the spontaneity of instant feedback which is so important in golf.
The prior patent art shows an apparatus similar to the apparatus used in the method defined by the present invention, but which is used in a different manner. U.S. Pat. No. 1,761,039 to Hazeltine is directed to a golf practice device in the form of a putting board having a covering of velour or velvet nap to simulate the closely cropped grass of a putting green. Hazeltine teaches that by brushing the nap surface of the covering, the path of a golf ball will appear after a ball has traveled over the brushed surface.
The Hazeltine patent does not teach or anticipate the need to examine the actual roll performance of a golf ball and the launch angle of the ball as it comes off a putter face but simply what path the ball takes to a target. Eighty years ago when Hazeltine patented his invention, analyzing roll was not important for a number of reasons. At that time the greens were slower and the grass was more course. The putters used in those days had 6 to 8 degrees of loft and hit a low chip to the hole. To simulate these conditions, the patent discloses the use of velour or velvet that would have simulated this surface having “sufficient softness to record the travel of a ball thereover.” An example of this would be the track produced by putting ball on a green in the early morning which is covered in dew. The ball's path would easily be defined along its entire journey to the hole. In the same way, Hazeltine does not anticipate using his putting practice apparatus to do anything other than show a golf ball's path. There is no teaching in the Hazeltine patent of using his patented apparatus for the purposes of the present invention.